This invention relates to frames for pictures and the like and, more particularly, to clamp assemblies used in constructing such frames.
It is conventional to construct picture frames by use of so-called "corners" or "corner clamps." The frame pieces employed are usually formed with channels (e.g., as a metal extrusion); end portions of the corner clamps are inserted into the channels of the frame pieces that are to be joined, after which the clamps are tightened to secure the assembly.
Two-piece clamp sets are described in U.S. Pat. Nos. 3,534,490 to Herbert, 3,965,601 and 4,122,617 to Nielson, and 4,516,341 to Jenkins. The use of a single angle piece at each corner of a frame is disclosed in U.S. Pat. Nos. 4,356,650 to Antonczyk, 4,403,434 to Jenkins, and 4,718,184 to Sherman, and a laterally acting connecting member is shown in UK patent No. 1,571,595, to Ciancimino.
Eisenloeffel U.S. Pat. No. 4,694,598 and Grove Canadian patent No. 1,178,439 provide clamping devices of box-like construction. In each case a screw passes through a rearward wall of the structure and into engagement with a pair of confronting, resilient arms; the ends of the arms are so formed as to cause them to be simultaneously urged forwardly and sidewardly by the screw, thereby to exert both transverse and lateral clamping forces. Canadian patent No. 1,168,445, to Zossimas, is generally similar in the embodiment shown in FIGS. 1 through 3, except that the arms on the clamp appear to produce only lateral force.
Despite the activity in the art exemplified by the foregoing, a need remains for a corner clamp assembly that is suitable for use in the assembly of frame pieces, which is incomplex and relatively facile and inexpensive to manufacture, is convenient to use with minimal need for adjustment or realignment after initial set-up, and is highly effective in producing simultaneously clamping forces in transverse and lateral directions.